1. Field of the Invention
The present invention relates to optical systems and more particularly to optical modulators having a semiconductor material in the modulating structure.
2. Brief Description of Prior Developments
Much work has been done recently on a wide range of opto-electronic devices based on the electric-field dependence of strong absorption resonances in semi-conductor quantum wells (QWs). These devices typically manipulate light having photon energies near the bandgaps of the quantum wells, corresponding to wavelengths around 1000 nanometers (nm) for gallium arsenide (GaAs) and low-indium-concentration InGaAs.
In a QW, a layer of one semiconductor material is sandwiched between cladding layers of a different material, with the electronic properties of the materials being such that an electric potential well (in the central layer) is formed between two electric potential barriers (in the cladding layers). The QW's small thickness, on the order of 100 angstroms, results in a quantization of charge-carrier motion in the thickness direction that leads to a formation of electron and hold sub-bands in the conduction and valence bands, respectively.
The efficiency of such opto-electronic devices may be increased by increasing the number of addressable pixels on the semiconductor material. There is, therefore, a need for a fabrication technique that increases the number of available addressable pixels by requiring a smaller contact and the indium bumps used to address the pixels.